Display device and method for driving same

Abstract

A display device is provided with: a display portion including a plurality of scanning lines, a plurality of data lines, and a plurality of pixel circuits; a scanning line drive circuit; and a data line drive circuit. The level of a data voltage applied to the data line decreases when a frame frequency is switched higher, and increases when the frame frequency is switched lower. This can prevent a display flicker when the frame frequency is switched. The level of the data voltage may change when the frame frequency is switched, and may return to its initial level over a plurality of frame periods. The timing of the control signal used to drive the display portion may change in accordance with the frame frequency to cause the length of the charging period of the pixel circuit to change in accordance with the frame frequency.

The invention claimed is: 
     
       1. A display device having a function of switching a frame frequency, the display device comprising:
 a display unit that includes a plurality of scanning lines, a plurality of data lines, and a plurality of pixel circuits; 
 a scanning line drive circuit configured to drive the scanning lines; and 
 a data line drive circuit configured to drive the data lines, wherein 
 a level of a data voltage applied to each of the data lines changes in accordance with the frame frequency, and 
 the level of the data voltage decreases when the frame frequency is switched higher, and the level of the data voltage increases when the frame frequency is switched lower. 
 
     
     
       2. The display device according to  claim 1 , wherein the level of the data voltage changes when the frame frequency is switched, and the level of the data voltage returns to an initial level over a plurality of frame periods. 
     
     
       3. The display device according to  claim 1 , further comprising a gradation conversion circuit configured to perform gradation conversion on a video signal in accordance with the frame frequency,
 wherein the data line drive circuit generates the data voltage based on a video signal after gradation conversion. 
 
     
     
       4. The display device according to  claim 1 , wherein the data line drive circuit includes a voltage generation circuit configured to generate the data voltage based on a video signal and the frame frequency. 
     
     
       5. A display device having a function of switching a frame frequency, the display device comprising:
 a display portion that includes a plurality of scanning lines, a plurality of data lines, and a plurality of pixel circuits; 
 a scanning line drive circuit configured to drive the scanning lines; and 
 a data line drive circuit configured to drive the data lines, wherein 
 a timing of a control signal used to drive the display portion changes in accordance with the frame frequency to cause a length of a charging period of each of the pixel circuits to change in accordance with the frame frequency, and 
 the length of the charging period decreases when the frame frequency is switched higher, and the length of the charging period increases when the frame frequency is switched lower. 
 
     
     
       6. The display device according to  claim 5 , wherein a timing at which a clock signal supplied to the scanning line drive circuit changes is advanced when the frame frequency is switched higher, and the timing is delayed when the frame frequency is switched lower. 
     
     
       7. The display device according to  claim 5 , wherein a timing at which a control signal indicating a start timing of application of a voltage to each of the data lines changes is delayed when the frame frequency is switched higher, and the timing is advanced when the frame frequency is switched lower. 
     
     
       8. The display device according to  claim 5 , further comprising a data line selection circuit configured to select a data line to which an output voltage of the data line drive circuit is applied from among a predetermined number of data lines,
 wherein a timing at which a control signal supplied to the data line selection circuit changes is delayed when the frame frequency is switched higher, and the timing is advanced when the frame frequency is switched lower. 
 
     
     
       9. A method for driving a display device that includes a display portion including a plurality of scanning lines, a plurality of data lines, and a plurality of pixel circuits, and having a function of switching a frame frequency, the method comprising:
 driving the scanning lines; and 
 driving the data lines, wherein 
 a level of a data voltage applied to each of the data lines changes in accordance with the frame frequency, and 
 the level of the data voltage decreases when the frame frequency is switched higher, and the level of the data voltage increases when the frame frequency is switched lower. 
 
     
     
       10. The method for driving a display device according to  claim 9 , wherein the level of the data voltage changes when the frame frequency is switched, and the level of the data voltage returns to an initial level over a plurality of frame periods.